固相萃取-气相色谱-质谱法检测不同基质蔬菜中百菌清残留

Determination of chlorothalonil residues with different substrates in vegetables by gas chromatography-mass spectrometry with solid phase extraction

目的 建立固相萃取-气相色谱-质谱法检测不同基质的蔬菜中百菌清残留的分析方法。方法 均质样品用乙腈(或酸化乙腈水溶液)超声提取,提取液用弗罗里硅土固相萃取柱(Florisil)净化,丙酮+正己烷(1∶9,V/V)混合液洗脱经氮吹浓缩至近干,用1. 00 ml正己烷溶解混匀,经HP-5MS毛细管色谱柱分离,气相色谱-质谱联用(GC-MS)选择离子扫描方式测定,内标法定量。结果 通过优化样品前处理和仪器条件,方法的标准曲线线性关系良好(r≥0. 999),方法检出限为0. 000 78 mg/kg,30种蔬菜在0. 10 mg/kg加标水平下(除洋葱加标水平5. 0 mg/kg)回收率在72. 0%~114%。结论 该方法准确可靠,可满足于不同基质蔬菜中百菌清残留的检测。

Objective To establish a method for the determination of chlorothalonil residues in vegetables with different substrates by gas chromatography-mass spectrometry with solid phase extraction(SPE-GC-MS).Methods The homoge-nized samples were ultrasonically extracted with acetonitile(or acidified acetonitrile aqueous solution),and the extracted solu-tion was purified by Florisil solid phase extraction column,eluted with mixed solution of acetone and hexane(1:9,V/V),concentrated to near dry under nitrogen flow.The residue was dissolved with 1.00 ml hexane and was separated by an HP-5 MS capillary column,dected by mass spectrometer with selective ion monitoring mode(SIM),and the quantification was performed by the intenal standard method.Results Through the optimiation of sample pretreatment and instrumental conditions,the line-arity of the standard curve was good(r≥0.99).The detection limit of the method was 0.00078 mg/kg,and the recoveries of 30 kinds of vegetables were in the range of 72.0%-114%at the level of0.10 mg/kg(5.0 mg/kg for onion).Conclusion The method is accurate and reliable,and could be used to detect chlorothalonil residues in different vegetables.